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When I got removed the use of atexit() I missed the fact that edit()
calls pw_error() which in turn calls exit().  Now edit() returns
its status so the temp file gets cleaned up nicely if the user makes
no changes or if an error occurred.  Problem noticed by deraadt@

/*	$OpenBSD: chpass.c,v 1.26 2002/07/31 22:08:41 millert Exp $	*/
/*	$NetBSD: chpass.c,v 1.8 1996/05/15 21:50:43 jtc Exp $	*/

/*-
 * Copyright (c) 1988, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static char copyright[] =
"@(#) Copyright (c) 1988, 1993, 1994\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)chpass.c	8.4 (Berkeley) 4/2/94";
#else
static char rcsid[] = "$OpenBSD: chpass.c,v 1.26 2002/07/31 22:08:41 millert Exp $";
#endif
#endif /* not lint */

#include <sys/param.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/uio.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

#include "chpass.h"
#include "pathnames.h"

extern char *__progname;

enum { NEWSH, LOADENTRY, EDITENTRY } op;
uid_t uid;
#ifdef	YP
int	use_yp;
int	force_yp = 0;
#endif

void	baduser(void);
void	kbintr(int);
void	usage(void);

int
main(int argc, char *argv[])
{
	struct passwd *pw = NULL, lpw;
	int i, ch, pfd, tfd, dfd;
	char *arg = NULL;
	sigset_t fullset;

#ifdef	YP
	use_yp = _yp_check(NULL);
#endif

	op = EDITENTRY;
	while ((ch = getopt(argc, argv, "a:s:ly")) != -1)
		switch(ch) {
		case 'a':
			op = LOADENTRY;
			arg = optarg;
			break;
		case 's':
			op = NEWSH;
			arg = optarg;
			break;
#ifdef	YP
		case 'l':
			use_yp = 0;
			break;
		case 'y':
			if (!use_yp) {
				warnx("YP not in use.");
				usage();
			}
			force_yp = 1;
			break;
#endif
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

#ifdef	YP
	if (op == LOADENTRY && use_yp)
		errx(1, "cannot load using YP, use -l to load local.");
#endif
	uid = getuid();

	if (op == EDITENTRY || op == NEWSH)
		switch(argc) {
		case 0:
			pw = getpwuid(uid);
#ifdef	YP
			if (pw && !force_yp)
				use_yp = 0;
			else if (use_yp)
				pw = ypgetpwuid(uid);
#endif	/* YP */
			if (!pw)
				errx(1, "unknown user: uid %u", uid);
			break;
		case 1:
			pw = getpwnam(*argv);
#ifdef	YP
			if (pw && !force_yp)
				use_yp = 0;
			else if (use_yp)
				pw = ypgetpwnam(*argv);
#endif	/* YP */
			if (!pw)
				errx(1, "unknown user: %s", *argv);
			if (uid && uid != pw->pw_uid)
				baduser();
			break;
		default:
			usage();
		}

	if (op == NEWSH) {
		/* protect p_shell -- it thinks NULL is /bin/sh */
		if (!arg[0])
			usage();
		if (p_shell(arg, pw, NULL))
			pw_error(NULL, 0, 1);
	}

	if (op == LOADENTRY) {
		if (uid)
			baduser();
		pw = &lpw;
		if (!pw_scan(arg, pw, NULL))
			exit(1);
	}

	/* Edit the user passwd information if requested. */
	if (op == EDITENTRY) {
		char tempname[] = __CONCAT(_PATH_VARTMP,"pw.XXXXXXXX");
		int edit_status;

		dfd = mkstemp(tempname);
		if (dfd == -1 || fcntl(dfd, F_SETFD, 1) == -1)
			pw_error(tempname, 1, 1);
		display(tempname, dfd, pw);
		edit_status = edit(tempname, pw);
		close(dfd);
		unlink(tempname);

		switch (edit_status) {
		case EDIT_OK:
			break;
		case EDIT_NOCHANGE:
			pw_error(NULL, 0, 0);
			break;
		case EDIT_ERROR:
		default:
			pw_error(tempname, 1, 1);
			break;
		}
	}

	/* Drop user's real uid and block all signals to avoid a DoS. */
	setuid(0);
	sigfillset(&fullset);
	sigdelset(&fullset, SIGINT);
	sigprocmask(SIG_BLOCK, &fullset, NULL);

	/* Get the passwd lock file and open the passwd file for reading. */
	pw_init();
	for (i = 1; (tfd = pw_lock(0)) == -1; i++) {
		if (i == 4)
			(void)fputs("Attempting lock password file, "
			    "please wait or press ^C to abort", stderr);
		(void)signal(SIGINT, kbintr);
		if (i % 16 == 0)
			fputc('.', stderr);
		usleep(250000);
		(void)signal(SIGINT, SIG_IGN);
	}
	if (i >= 4)
		fputc('\n', stderr);
	pfd = open(_PATH_MASTERPASSWD, O_RDONLY, 0);
	if (pfd == -1 || fcntl(pfd, F_SETFD, 1) == -1)
		pw_error(_PATH_MASTERPASSWD, 1, 1);

#ifdef	YP
	if (use_yp) {
		if (pw_yp(pw, uid))
			pw_error(NULL, 0, 1);
		else {
			pw_abort();
			exit(0);
		}
	} else
#endif	/* YP */
	{
		/* Copy the passwd file to the lock file, updating pw. */
		pw_copy(pfd, tfd, pw);

		/* Now finish the passwd file update. */
		if (pw_mkdb(pw->pw_name, 0) == -1)
			pw_error(NULL, 0, 1);
	}

	exit(0);
}

void
baduser(void)
{

	errx(1, "%s", strerror(EACCES));
}

void
kbintr(int signo)
{
	struct iovec iv[5];

	iv[0].iov_base = "\n";
	iv[0].iov_len = 1;
	iv[1].iov_base = __progname;
	iv[1].iov_len = strlen(__progname);
	iv[2].iov_base = ": ";
	iv[2].iov_len = 2;
	iv[3].iov_base = _PATH_MASTERPASSWD;
	iv[3].iov_len = sizeof(_PATH_MASTERPASSWD) - 1;
	iv[4].iov_base = " unchanged\n";
	iv[4].iov_len = 11;
	writev(STDERR_FILENO, iv, 5);

	_exit(1);
}

void
usage(void)
{

#ifdef	YP
	(void)fprintf(stderr,
	    "usage: %s [-l%s] [-a list] [-s newshell] [user]\n",
	    __progname, use_yp ? "y" : "");
#else
	(void)fprintf(stderr, "usage: %s [-a list] [-s newshell] [user]\n",
	    __progname);
#endif
	exit(1);
}